Daryl Obert share some tips for working with the Maya Blend Shape Deformers imparting some great information for new and advanced users.
Some cool tips to get the most out of Maya’s Blendshapes
Daryl quickly looks at adding an “in-between” blend shape that will transition through a pose sequence. Daryl also moves into some painting techniques that will allow you create new blend shapes from existing shapes, mixing poses for new blends.
What if you had topology changes to a model that already has blend shapes created for it? Maya has a Bake Topology Targets tool which will propagate the changes down to the blend shapes.